Well… Australia is a big place… with many different climates… and in a lot of those climates ‘Peace’ is, as you say, spectacular. If I am to breed roses which are good for Australia then I need to think outside the state that I’m in, which has less than 3% of the country’s population. It does poorly in Tasmania, but there is a need for better drought and heat resistant garden plants in hot dry areas, of which Australia has many, and these are the areas where ‘Peace’ excells. We need roses that do well in hot humid areas, where ‘Peace’ does not do well but combined with Teas, Noisettes, or Chinas… or even persica hybrids… maybe it could produce something of merit for these areas. We have absolutely no need for roses that can survive zone 2-5 winters unless they too possess tolerances to heat, drought, and very high humidity along the coasts.
I onced live in northwest New South Wales in a farming town called Moree. It was 5 hours inland and an hour from the Queensland border. In summer it was so hot you felt like you’d melt. I use to spend the school holidays cotton chipping (you get put in a chipping gang at one end of a 20,000 acre paddock with a hoe and told to chip out the weeds from the cotton fields and I’d earn 120 tax free dollars each day which was great to supplment a beginning teacher’s wage 20 years ago… we’d start at 3am and finish by 2pm because it was too hot after that and then spend the afternoon resting tired muscles soaking in the hot thermal pool in town). At times the temperature out in the fields would get to over 50 degrees Celcius. Hottest we ever measured was 52 (125.6F) out in the field. I grew ‘Peace’ out there and it was magnificent.
Tasmania has only 500,000 people in it so if I am to think further afield than where I am now then diversity is among the things that I’d like to have. This is why I keep looking at ‘Peace’ because what it looked like in Moree will be forever burned into my mind.
I think it’s sometimes hard for some of you guys over there to get a good handle on what we are facing here, climatically. Sure you guys have hot areas… you have some insanely hot areas… however, the entire country here is, using the USDA zones as a point of reference, rated at zone 9 to zone 13 or higher and much of the country is in fact arid with narrow bands of temperate to tropical land along the coast. We are, in general, the driest continent on the planet (not here where I get nearly a metre of rainfall a year or the west coast of Tas which receives over 3m of rainfall/year, but most the east coast is dry as a bone. Hobart is in this rain shadow and is the driest capital city in the country). There may be some areas that fall into zone 8 or even 7 but these are very sparsely populated. Even down here in Tasmania, where I am only 2,000km from Antarctica, I’m still in the equivalent of your zone 9B.
I live right at the bottom of the country, along the north coast of Tas bang in the middle 
I can grow Gallica here but you don’t have to go very far north before they are a waste of time for the rest of the country. Even mine don’t flower every year because we need a colder than usual winter to give them enough chill hours. We get pretty stiff frosts and it snows once or twice a year here but it never settles. It does up on the hills behind us (Google Cradle Mountain which is about 50km south of here) but very rarely down here. It gets cold in other areas too but it’s the length of time it is cold for that messes roses like Gallica up further north. They still grow, but flowering is unreliable and David Austin roses grow like medusa instead of well mannered rose bushes.
So that’s why I am thinking about ‘Peace’. If I concentrated on breeding roses that only did well for me, here in Tasmania, then it would have very limited use anywhere else because roses, in general, grow better here than anywhere else in the country because we have a milder climate and a long cold winter. I’m just wondering whether you can ‘teach an old dog new tricks’.
Jim, I’ve not seen ‘Double Knockout’ here yet. I grow ‘Knock Out’ though and seems pretty good down here though George has mentioned it grew poorly up in Sydney where it is far hotter and the humidity is pretty extreme.